Adapter panel with lateral sliding adapter arrays

ABSTRACT

An adapter panel arrangement including a chassis and a panel of adapters. The adapters defining rearward cable connections and forward cable connections of the panel arrangement. Openings permitting access to the rearward and forward cable connections of the adapters are provided. The chassis further including a removable rear chassis portion to provide access to cable routing areas within the chassis interior.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. application Ser. No.11/655,760, filed Jan. 19, 2007; which application is incorporatedherein by reference.

FIELD OF THE INVENTION

This disclosure relates to devices for use in the telecommunicationsindustry, and associated methods. More specifically, this disclosurerelates to a termination panel for use in the telecommunicationsindustry, and methods associated with termination panels.

BACKGROUND OF THE INVENTION

Many local area networks and telecommunication systems utilizetermination panels to provide cross-connections betweentelecommunications equipment. Demand for greater telecommunicationservices has prompted the increase in circuit densities of terminationpanels. Notwithstanding the advances made in the art, there is acontinuous need for further advances to improve upon high-densitytermination panels and associated methods. Improvements are needed, forexample, to enhance termination access and cable management associatedwith installation, maintenance, repair, upgrade, and cross-connectionprocedures related to termination panels.

SUMMARY OF THE INVENTION

The present disclosure relates to an adapter panel arrangement includinga chassis and a panel of adapters. The adapters define open rearwardcable connections and open forward cable connections of the panelarrangement. The adapters are arranged in arrays that slideindependently of other arrays to provide access to the open rearward andopen forward cable connections. Access to the connections is furtherprovided by removable access panels attached to the top wall of thechassis and bottom access openings formed in a sliding drawer. Access tothe interior region of the chassis is provided by a removable rearchassis wall.

A variety of examples of desirable product features or methods are setforth in part in the description that follows, and in part will beapparent from the description, or may be learned by practicing variousaspects of the disclosure. The aspects of the disclosure may relate toindividual features as well as combinations of features. It is to beunderstood that both the foregoing general description and the followingdetailed description are explanatory only, and are not restrictive ofthe claimed invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front perspective view of one embodiment of an adapter panelarrangement, in accordance with the principles disclosed, shown with adrawer of the adapter panel arrangement in an open position;

FIG. 2 is a front perspective view of the adapter panel arrangement ofFIG. 1, shown with the drawer in a closed position;

FIG. 3 is a front perspective view of the adapter panel arrangement ofFIG. 2, shown with a cover of the arrangement closed;

FIG. 4 is a rear perspective view of the adapter panel arrangement ofFIG. 1;

FIG. 5 is a side elevation view of the adapter panel arrangement of FIG.4;

FIG. 6 is a top plan view of the adapter panel arrangement of FIG. 5;

FIG. 7 is a top perspective view of one embodiment of a sliding framepiece and an adapter array of the adapter panel arrangement of FIG. 1,shown in isolation;

FIG. 8 is a side elevation view of the sliding frame piece and adapterarray of FIG. 7;

FIG. 9 is a top plan view of the sliding frame piece and adapter arrayof FIG. 7;

FIG. 10 is a side elevation view of one embodiment of a guide of theadapter panel arrangement of FIG. 1, shown in isolation;

FIG. 11 is a bottom perspective view of the guide of FIG. 10;

FIG. 12 is a top plan view of the guide of FIG. 10, and a portion of thesliding frame piece of FIG. 9;

FIG. 13 is a front perspective view of the adapter panel arrangement ofFIG. 2, shown with an adapter array positioned in a forward position;

FIG. 14 is a side elevation view of the adapter panel arrangement ofFIG. 13; and

FIG. 15 is a top plan view of the adapter panel arrangement of FIG. 14.

DETAILED DESCRIPTION

Reference will now be made in detail to exemplary aspects of the presentdisclosure that are illustrated in the accompanying drawings. Whereverpossible, the same reference numbers will be used throughout thedrawings to refer to the same or like parts.

FIG. 1 illustrates a distribution frame or adapter panel arrangement 10in accordance with the principles disclosed. The adapter panelarrangement 10 is designed to provide a high density of cableterminations, yet facilitate access to the cable terminations from therear during installation procedures, and from the front duringpost-installation procedures.

The adapter panel arrangement 10 of the present disclosure generallyincludes a chassis 12 having an interior 14. The interior 14 is definedby a top wall 16, a bottom wall 18, a rear wall 20, and side walls 22,24. The adapter panel arrangement 10 also includes a sliding drawer 34that slides between an open position (FIG. 1) and a closed position(FIG. 2). A front cover 26 is attached to the sliding drawer 34. Whenthe drawer 34 is in the closed position, the front cover 26 encloses theinterior 14 of the chassis 12 when closed (FIG. 3) and provides accessto the interior 14 when open (FIG. 2).

Referring now to FIGS. 1 and 2, the adapter panel arrangement 10includes a framework structure 30 (FIG. 1) that is attached or mountedto the drawer 34. A panel of adapters 32 is mounted to the frameworkstructure 30. As will be described in greater detail hereinafter, thedrawer 34 is designed to slide outward from the chassis 12 primarily forinstallation purposes. That is, the drawer 34 can be slid to the openposition during installation or assembly of the adapter panelarrangement, but is position in the closed position (FIG. 2) duringoperative use of the arrangement 10. During operative use, the frameworkstructure 30 and the panel of adapters 32 are located within theinterior 14 of the chassis 12 and the drawer 34 is in the closedposition (FIG. 2). A user accesses the panel of adapters 32 from a frontopening 28 of the chassis 12 without sliding the drawer 34 forward.

Referring again to FIG. 1, the panel of adapters 32 includes a facepanel 42 that defines a number of openings 44 (only one shown). Adapters46 are mounted within the openings 44. In the illustrated embodiment,the adapters are LC type adapters; however, other types of adapters,such as SC, ST, FC and MPO type adapters can also be used in accordancewith the principles disclosed. Further, in the illustrated embodiment,the adapters 46 are blocked or grouped; each adapter block 58 includingeight adapters 46 (four adapter pairs). Other number of adapters can beprovided in an adapter block, such as four adapters (two adapter pairs),for example; the openings in the face panel 42 being correspondinglysized to receive the four-adapter blocks. Alternative, single adapterscan be used and mounted with openings sized to receive the singleadapters.

The openings 44 of the face panel 42 are arranged in rows; each row ofmounted adapter blocks 58 defines an adapter array 48. What is meant bya row is that the openings 44 are arranged in a generally horizontalalignment, as opposed to being arranged in a column or in a verticalalignment; accordingly, the adapter arrays 48 are generally horizontaladapter arrays.

Referring now to FIGS. 1 and 4, the adapters 46 of the adapter blocks 58each includes a front connection end 50 (FIG. 1) and a rear connectionend 52 (FIG. 4). When mounted within the openings 44, the frontconnection ends 50 of the adapters 46 are located toward the frontopening 28 of the chassis 12, and the rear connection ends 52 of theadapters 46 are located toward the rear wall 20 of the chassis 12. Thefront connection ends 50 of the adapters 46 define open frontward cableconnection locations 54 (FIG. 2) of the face panel 42. The rearconnection ends 52 of the adapters 46 define open rearward cableconnection locations 56 (FIG. 4) of the face panel 42.

What is meant by “open cable connection locations” are locations thatare provided in an open region in the chassis 12, as opposed to aconnection location that is enclosed within a housing or module, thehousing or modules in turn being mounted within the chassis. That is,the panel of adapters 32 is a panel of unenclosed adapters 46 that arenot enclosed relative to the other adapters 46 on the face panel 42.While the panel of adapters itself is enclosed within the chassis 12,the plurality of adapters 46, and each of the adapter arrays 48 are notenclosed separately from the other adapters 46 or the other adapterarrays 48.

Referring now to FIGS. 1, 5 and 6, the adapter arrays 48 of the facepanel 42 are designed to slide in a lateral direction independent ofother adapter arrays. In particular, the face panel 42 is defined by anumber of separate panel sections 60. In the illustrated embodiment,each separate panel section defines one row of openings in which theblocks 58 of unenclosed adapters 46 are mounted, i.e., each panelsection 60 contains one adapter array 48. In other embodiments, thepanel sections can include, for example, two rows of openings thatreceive four-adapter blocks, for example; this panel section embodimentcontaining two adapter arrays.

The face panel 42 of the adapter panel arrangement 10 illustratedincludes six panel sections 60—two panel sections 60 positionedside-by-side, and stacked three panel sections high (see FIG. 1). Eachpanel section 60 contains six blocks 58 having eight adapters 46 for atotal of 288 frontward connection locations and rearward connectionlocations. Each separate panel section 60 is designed to selectivelyslide in a forward, lateral direction (A) independent of the other panelsections. The forward, lateral direction (A) is a direction extendingbetween the front opening 28 and the rear wall 20, as opposed to adirection which is transverse to the bottom wall 18 of the chassis 12,for example.

Referring to FIGS. 7-9, each separate panel section 60 of the panel ofadapters 32 is attached to a sliding frame piece 62. The sliding framepiece 62 includes a pair of elongated rail members 64. In theillustrated embodiment, the elongated rail members 64 include a forwardrail portion 84 that extends forwardly from the panel section 60, and arearward rail portion 86 that extends rearwardly from the panel section60. The sliding frame piece 62 can include a cross-support 88 tomaintain the structural relationship of the rail members 64.

The pairs of elongated rail members 64 are arranged to engage and slidewithin pairs of guides 66 (one shown in FIGS. 10-12) that are mounted tothe framework structure 30 (FIG. 1) of the arrangement 10. The railmembers 64 and the guides 66 include a stop arrangement 68 that limitsthe sliding motion of the panel sections 60 between a rearward position(see the top panel section 60 in FIG. 5) and a forward position (see thebottom panel section 60 in FIG. 5).

Referring to FIGS. 9-12, the stop arrangement 68 (FIG. 12) is defined byat least one projection 70 (FIGS. 10 and 11) located on each guide 66 ofthe pair of guides, and first and second pockets or detents 72, 74 (FIG.9) formed in the rail members 64. In the illustrated embodiment, twoprojections 70 (upper and lower projections) are provided on each of theguides 66. Correspondingly, upper and lower detents 72, 74 (see FIG. 8)are formed in the rearward rail portions 86 of the rail members 64.While the illustrated embodiment depicts the detents 72, 74 formed inthe rail members 64 and the projections 70 provided on the guides 66, itis contemplated that the detents can be formed in the guides 66 and theprojection correspondingly provided on the rail members 64.

Referring still to FIGS. 9-12, when the panel section 60 is positionedin the rearward position, the projections 70 of the guides 66 seatwithin the first detents 72 of the rail members 64 to retain the panelsection 60 in the rearward position. The guides 66 are flexiblyconstructed so that when the panel section 60 is pulled forward, theprojections 70 un-seat and slide along top and bottom surfaces 76, 77(FIG. 8) of the rail members 64. Referring to FIG. 12, when the panelsection 60 reaches the forward position, the projections 70 seat withinthe second detents 74 of the rail members 64. This stop arrangement 68indicates to a user when the panel section 60 has reached thepredetermined forward position, and similarly, the rearward position.

Referring back to FIG. 5, in general, the stop arrangement 68 providesan indication of when the panel section 60 has moved a lateral distanceD forward from the rearward position to the forward position. In oneembodiment, the lateral distance D is no more than about 4.0 inchesforward from the rearward position. In the illustrated embodiment, thelateral distance D is about 1.7 inches. Providing such an indication tothe user prevents the user from moving the panel section 60 a distancebeyond that which cables interconnected to the panel section 60 willallow.

In particular, as previously described, the present panel arrangement 10is designed such that the drawer 34 is intended to slide only duringinstallation procedures, as opposed to post-installation or duringoperative use. Referring to FIG. 4, during installation, cables 36, suchas fiber optic cables, are routed into the chassis 12 through rearopenings 38 and terminated to the open rearward connection locations 56of the face panel 42 (i.e., the rear connector ends 52 of the adapters46).

The fiber optic cables 36 have a predetermined length that can be routedabout cable storage spools or structures (see e.g., 78, 80 in FIG. 1).The predetermined lengths of the cables, however, do not have enoughslack to accommodate drawer 34 movement during operative use, and thearrangement 10 does not have devices such as sliding radius limitersthat take up or manage excessive movement of such cable slack.

In present panel arrangement 10, the predetermined lengths of the cablesgenerally accommodate only the limited sliding movement of the panelsections 60. That is, while the drawer 34 may be slid out for purposesof installation, or for repairs requiring access to the region behindthe panel of adapters 32, the drawer 34 is not intended to slide forpurposes of accessing the panel of adapters 32 during operative use ofthe adapter panel arrangement 10. Operative use and access to the panelof adapters 32 is instead provided by the sliding movement of the panelsections 60 relative to the sliding movement of the drawer 34.

In general, the lateral sliding movement of the panel sections 60provides access to the open cable connections (e.g., 54, 56) defined bythe adapter arrays 48. Access to the open connection locations (e.g.,54, 56) of the face panel 42 is important in two primary instances: thefirst instance being during installation (e.g., during initial installor assembly, or during repair, replacement, or upgrade of the cableterminations at the rearward connection locations 56 of the panel 32);the second instance being after installation during operative use of thearrangement 10.

Referring back to FIGS. 1 and 4, during installation, the drawer 34 ispulled out to the open position. As previously described, a technicianroutes the fiber optic cables 36 through the rear openings 38 of thechassis 12 and terminates the cables to the open rearward connectionlocations 56 of the panel of adapters 32. To provide better access tothe rear connection ends 52 of the adapters 46 defining the rearwardconnection locations 56, one of the adapter arrays 48 is positioned inthe rearward position (e.g., the top array), while the remaining adapterarrays (e.g., the arrays located beneath the top array (see also FIGS. 5and 6)) are positioned in the forward position. In this configuration,the technician has better access to the open rearward connectionlocations 56 of the one panel section 60 positioned in the rearwardposition. Once cable terminations to that particular adapter array 48are complete, that adapter array can be slid forward and the next arrayto which cables are to be terminated slid rearward.

Referring to FIG. 4, to provide even further access to the open rearwardconnection locations 56, the top wall 16 of the chassis 12 includesremovable access panels 92. Referring to FIG. 2, each of the panels 92slides outward in a direction B from the top wall 16 of the chassis 12.In FIG. 2, the panels 92 are shown engaged with the top wall 16. Inparticular, each panel 92 is locked in place by a flexible tab 94 thatengages a hem or roll 98 formed in a top wall portion 100 of the topwall 16. The flexible tab 94 is defined by slots 96 formed in the panel92. The hem or roll 98 is formed by bending or rolling a section of thetop wall 16 over on itself; although structure can be attached to thetop wall as an alternative to providing a hem.

To slide one of the panels 92 out, the flexible tab 94 is flexeddownward beyond the hem or roll 98 formed in the top wall portion 100.The panel is then slid out in the direction shown in FIG. 2 and removedto define a top wall opening 104 (see e.g., FIG. 15) located adjacent tothe front opening 28 of the chassis 12. The top wall opening 104provides further access to the open rear connection locations 56. Tore-attach the panel 92, the panel 92 is place in relation to the topwall opening 104, the flexible tab 94 is flexed downward, and the panel92 is then slid back into place. As shown in FIG. 15, retaining flanges102 are formed in the top wall 16 at the top wall openings 104. Theretaining flanges 102 support the panels 92 when attached to the topwall 16 of the chassis 12.

The open rearward connection locations 56 are typically access onlyduring installation procedures, with the exception of repairs orupgrades, for example. The open frontward connection locations 54,however, are accessed on a more regular basis to providecross-connections between telecommunications equipment. Such use isreferred to as operative use, or use that is post-installation andprimarily involves maintaining or establishing cable terminations at thefront connection ends 50 of the adapters 46.

Referring now to FIGS. 13-15, the adapter panel arrangement 10 is shownin operative use. During operative use, the panel of adapters 32 isaccessed through the front opening 28 of the chassis 12, with the drawer34 positioned in the closed position.

As previously described, the cables 36 that enter the interior 14 of thechassis 12 through rear openings 38 are terminated to the open rearconnection locations 56 of the panel of adapters 32. Referring to FIG.13, jumper cables or patching cables 40 are also terminated to the panelof adapters 32; and in particular, to the open frontward connectionlocations 54 of the panel 32. The patching cables 40 provide thecross-connections between the adapter panel arrangement 10 and othertelecommunications equipment (not shown). The patching cables 40 arerouted from the front opening 28 and through side openings 90 (FIG. 3)of the chassis 12 to cable routing structure (e.g., channels, not shown)of the telecommunications system.

Because of the high-density arrangement of the adapters 46, each panelsection 60 of the panel of adapters 32 slides forward to separate theassociated adapter array 48 from the other arrays. By separatelypositioning the panel section 60 and the associated adapter array 48forward, a technician can more easily grasp a particular connector of apatching cable 40, and/or more easily terminate a patching cable to aparticular adapter 46 of the forwardly-positioned array. In addition,and as previously described, the access panels 92 (FIG. 13) of the topwall 16 can be removed (as shown in FIG. 15) to provide even furtheraccess to the open frontward connection locations 54 of the panelsections.

Referring again to FIG. 13, the forward rail portion 84 of the railmember 64 can be used as a handle to pull the panel section 60 forward.Alternatively, the user can slide the panel section 60 forward bygrasping a retaining ring 82 attached to the rail member 64 of thesliding frame piece 62. In the illustrated embodiment, the retainingrings 82 are attached to the ends of outer rail members 64 of thesliding frame piece 62 to protect the patching cables 40 from exceedinga minimum bend radius.

Referring still to FIG. 13, additional access to the adapters 46 isprovided through cut-outs or bottom access openings 106 located adjacentto the front opening 28 of the chassis. The bottom access openings 106are formed in the drawer 34 of the chassis 12. As can be understood, thefront connection end 50 of the adapters 46 on the lower-most panelsection 60 can be difficult to access as finger space between thelower-most adapters and the drawer 34 is limited. To better access tothose particular adapters during operative use, a technician simplyslides the lower-most panel section 60 outward relative to the drawer 34such the that lower-most panel section 60 is adjacent the cut-out oropening 106. The opening 106 provides additional finger space equal tothe thickness of the drawer. In the illustrated embodiment, the additionfinger space is approximately ¼ of an inch.

The bottom access openings 106 also provide better access to thelower-most adapters during installation or repair procedures. Referringto FIGS. 5 and 6, during an install, for example, a technician can slidethe drawer 34 outward using the bottom access openings 106 as handles,slide the lower-most panel 60 outward adjacent to the bottom accessopening 106 (FIG. 6), and then reach through the bottom access opening106, from beneath the drawer 34, to access the front connection ends ofthe adapters on the lower-most panel. Referring to FIG. 6, in theillustrated embodiment, the bottom access openings 106 have a length L.Preferably, the length L spans a substantial majority of the distance D2of which the plurality of adapters 46 span.

Referring back to FIG. 4, the present chassis 12 is also configured toprovide access to the interior 14 of the chassis through the rear. Inparticular, the rear of the chassis 12 is partly defined by a removablerear chassis portion 108 that provides access to the chassis interior 14when initially installing cables, for example. In the illustratedembodiment, the removable rear chassis portion 108 is a two-part chassisportion. A first part 110 of the removable rear chassis portion 108partly defines the top wall 16 of the chassis, and a second part 112defines the rear wall 20.

The rear chassis portion 108 is detachably secured to the remainder ofthe chassis 12 by latches 114. To access the interior 14 of the chassis12, the rear chassis portion 108 is unlatched and removed. The firstpart 110 of the rear chassis portion 108 has a depth D1 that exposes theinterior to provide access to interior cable routing areas. In theillustrated embodiment, the depth D of the part 110 of the chassisportion provides an exposed opening in the top wall that is at leastabout 5 inches. The exposed opening also extends the width W of thechassis (i.e., extends from one side wall 22 of the chassis to the otherside wall 24). The exposed opening through the top wall 16, in additionto the removal of the rear wall 20 aids in routing cables within theinterior of the chassis 12.

While the present disclosure is described with respect to use in a fiberoptic application, the disclosed panel arrangement can be adapted foruse in other applications. For example, in some applications, coppercables may be used exclusively from fiber optic cables; and accordinglyvarious types of wire terminations or wire connectors can be provided onthe face panel of the arrangement. Still, in other applications havinghybrid cabling, or applications having both types of fiber optic andcopper cabling, the face panel of the arrangement can be provided with acombination of fiber optic and copper connectors and/or adapters.

In general, the present adapter panel arrangement 10 provides ahigh-density adapter panel arrangement while facilitating access tootherwise crowded front and rear connection locations. Because of theaccess design of the present arrangement, the amount of space utilizedon racks and cabinets is minimized; or, in the alternative, allows forexpansion and upgrade of systems having spatial constraints, as moredensely packed connection locations are provided without sacrificingeffective access to the connection locations.

The above specification provides a complete description of the presentinvention. Since many embodiments of the invention can be made withoutdeparting from the spirit and scope of the invention, certain aspects ofthe invention reside in the claims hereinafter appended.

1. A chassis arrangement, comprising: a) a chassis housing having aninterior, the chassis housing including a removable rear chassisportion, the removable rear chassis portion including: i) a first partthat partially defines a top chassis wall; and ii) a second part thatdefines a rear chassis wall; b) wherein the first part of the rearchassis portion provides an exposed opening in the top chassis wall whenthe rear chassis portion is removed, access to cable routing areaslocated within the interior of the chassis housing being providedthrough the exposed opening in the top chassis wall.
 2. The chassisarrangement of claim 1, wherein the removable rear chassis portionincludes latches that detachably secure the rear chassis portion to aremainder of the chassis housing.
 3. The chassis arrangement of claim 1,wherein the exposed opening has a depth of at least about 5 inches. 4.The chassis arrangement of claim 1, wherein the exposed opening extendsthe width of the chassis housing.
 5. The chassis arrangement of claim 1,wherein the exposed opening extends the width of the chassis housing andhas a depth of at least about 5 inches.
 6. A chassis arrangement,comprising: a) a chassis housing including a top wall, a bottom wall,and opposing side walls; b) a drawer that slides relative to thechassis; c) a panel mounted to the drawer, the panel including aplurality of adapters; and d) a bottom access opening formed in thedrawer, the bottom access opening being located to provide access tofront connections of the adapters of the panel; e) wherein duringoperative use, the bottom access opening provides access to the frontconnections of the adapters by increasing finger space between the paneland the drawer.
 7. The arrangement of claim 6, wherein the panel slidesoutward toward a front opening of the chassis housing.
 8. Thearrangement of claim 7, wherein the bottom access opening is located toprovide access to the front connections of the adapters of the panelwhen the panel is slid outward toward the front opening of the chassishousing.
 9. The arrangement of claim 6, wherein the bottom accessopening is an elongated opening extending a length, the length spanninga substantial majority of the distance of which the adapters of thepanel span.
 10. The arrangement of claim 6, wherein during installationprocedures, the bottom access opening provides access to the frontconnections of the adapters by permitting a technician to reach throughthe bottom opening when the drawer is positioned in an open positionrelative to the chassis.
 11. The arrangement of claim 6, furtherincluding a top access opening formed in the chassis housing, the topaccess opening being located adjacent to a front opening to provideaccess to the adapters of the panel.
 12. The arrangement of claim 11,wherein the top access opening is provided by removal of panels attachedto the top wall of the chassis housing.
 13. The arrangement of claim 11,wherein the panels slide outward from the chassis housing to provideaccess to the adapters of the panel through the top access opening. 14.A chassis arrangement, comprising: a) a chassis housing including a topwall, a bottom wall, and opposing side walls; b) a drawer that slidesrelative to the chassis; c) a panel mounted to the drawer, the panelincluding a plurality of adapters; and d) a bottom access opening formedin the drawer, the bottom access opening being located to provide accessto front connections of the adapters of the panel; e) wherein the bottomaccess opening is elongated, the elongated bottom access openingextending a length that spans a substantial majority of the distance ofwhich the adapters of the panel span.
 15. A chassis arrangement,comprising: a) a chassis housing having an interior, the chassis housingincluding a removable rear chassis portion, the removable rear chassisportion including: i)a first part that partially defines a top chassiswall; ii)a second part that defines a rear chassis wall; and iii)latches that detachably secure the rear chassis portion to a remainderof the chassis housing; b) wherein removal of the rear chassis portionexposes cable routing areas provided within the interior of the chassishousing.
 16. The chassis arrangement of claim 15, wherein the first partof the rear chassis portion provides an exposed opening in the topchassis wall when the rear chassis portion is removed, the exposedopening having a depth of at least about 5 inches.
 17. The chassisarrangement of claim 15, wherein the first part of the rear chassisportion provides an exposed opening in the top chassis wall when therear chassis portion is removed, the exposed opening extending the widthof the chassis housing.
 18. The chassis arrangement of claim 15, whereinthe first part of the rear chassis portion provides an exposed openingin the top chassis wall when the rear chassis portion is removed, theexposed opening extending the width of the chassis housing and having adepth of at least about 5 inches.